Page 9 - Caldera Volcanism Analysis, Modelling and Response

viii Contents

11. Hydrothermal Fluid Circulation and its Effect on Caldera Unrest 393
Micol Todesco
1. Introduction 394
2. The Hydrothermal Fluid Circulation 395
3. Modelling of Hydrothermal Fluid Circulation 397
4. Hydrothermal Systems and Volcano Monitoring 400
5. An Example of Assessing the Role of Hydrothermal Processes During Unrest:
Solfatara (Phlegrean Fields Caldera, Italy) 404
6. Discussion and Conclusions 409
Acknowledgments 410
References 410

12. Deciphering Causes of Unrest at Explosive Collapse Calderas: Recent
Advances and Future Challenges of Joint Time-Lapse Gravimetric and
Ground Deformation Studies 417
Joachim Gottsmann and Maurizio Battaglia
1. Introduction 418
2. The Subsurface Beneath Calderas: Hydrothermal Versus Magmatic Reservoirs 419
3. Joint Ground Deformation and Gravimetric Survey 420
4. Vertical Gravity–Height Gradients 423
5. Single and Distributed Sources 424
6. The Search for Causative Sources of Unrest: Recent Examples
of Integrated Studies from the Long Valley, Campi Flegrei and
Las Can ˜adas Calderas 427
7. The Problem of Aliasing of Time-Lapse Micro-Gravity Data 437
8. The Effect of Lateral Discontinuities on Ground Deformation and
Residual Gravity Changes 437
9. Summary, Conclusions and Outlook 439
Acknowledgements 442
References 442
13. The Failure Forecast Method: Review and Application for the Real-Time
Detection of Precursory Patterns at Reawakening Volcanoes 447
Marta Ta ´rraga, Roberto Carniel, Ramon Ortiz and Alicia Garcı ´a
1. Introduction 448
2. Theory of Precursors 449
3. The Theory of the Material Failure Forecast Method (FFM) 450
4. Techniques of Analysis 453
5. Viscoelastic Model 453
6. Seismicity as the Observable for FFM 454
7. FFM Applied to the Studies of Volcanoes 456
8. Conclusions 465
Acknowledgements 466
References 466